As an example of cutting inserts usable for a grooving process or the like, Patent document 1 discloses a grooving tool. For example, in FIGS. 14 to 16 of Patent document 1, a plurality of breaker projections are formed and the height of these projections is increased stepwise as departing from an end flank surface. Specifically, the height of the projections is increased stepwise in the following order: the first stage projection, the second stage projection, and the third stage projection as departing from the end flank surface. In FIGS. 15 and 16 of Patent document 1, an auxiliary projection higher than the first stage projection is interposed between the first stage projection and the second stage projection. The auxiliary projection is used for discharging chips when a cutting process, which is called a cross-feed process in a direction perpendicular to a groove direction, is performed in the grooving process.
In the above grooving tool, however, the height of the projections is increased stepwise as departing from the end flank surface. Therefore, for example, when a workpiece is subjected to the grooving process and a cut-off process, chips may climb over the first stage projection and collide with the auxiliary projection, thus damaging the auxiliary projection. Therefore, when the workpiece after being subjected to these processes is then subjected to a chamfering process, or a process of cutting a wall surface on one side of a groove by using one end portion of an end cutting edge in order to increase a groove width, there has been a risk that the chips could not be sufficiently discharged due to the auxiliary projection.
Hence, there is a need for a cutting insert having excellent chip discharge performance in the grooving process and the cross-feed process.
Patent Document 1: Japanese Unexamined Patent Publication No. 2006-150584